This invention relates to fuel injection valves for internal combustion engines, and more particularly to pulse operated type fuel injection valves.
In order to minimize the amount of exhaust emissions in internal combustion engines, it is widely recognized that fuel and air should be mixed as evenly as possible. Further, it is widely recognized that in order to bring about this desired even mixing, that it is necessary that the fuel be atomized as finely as possible.
In the past it has been recognized that the desired atomization can be achieved by causing the fuel to be injected from the valve in a conical pattern. This conical pattern injection can be brought about by using a pintle valve arrangement. A typical patent showing a valve arrangement of this type is U.S. Pat. No. 3,450,353.
Another method utilized to cause a conical injection pattern is to employ some means for imparting a radial velocity component to the fuel as it flows from the injection valve. Typical devices employing this method are shown in U.S. Pat. Nos. 3,241,768; 3,528,613; 3,567,135 and 4,033,513.
In the prior art, it has been known to employ flat-faced armature-pole piece arrangements in electromagnetic fuel injection valves. As used herein, the term "flat-faced armature" is used to denote an armature-pole piece arrangement in which substantially all of the force of magnetic attraction between the two is parallel to the axis of the valve.
In addition, electromagnetic fuel injection valves employing ball type valves have been known in the prior art.
In general, all of the prior art electromagnetic fuel injection valves require tight tolerances on many of their components, most notably the output orifice, the valve seat, the valve element, and in many cases the fuel breakup or swirl device. Because of the necessity for such tight tolerances, the overall cost of the valve is excessive. Consequently, if the need for tight tolerances can be eliminated, it is clear that the overall cost of the fuel injection valve can be greatly reduced.